Note: This is a very WordPress-specific question.
In the WordPress admin, in Appearance > Menus > Theme Locations, I'm selecting "which menu appears in each location" (I've got two menus running on TwentyTen) and everything seems to be running fine. However, every once in a while the setting will clear -- I'll check the Admin panel and my selections have disappeared. It's ruining my menu appearance, making each menu appear twice, stacked on top of each other.
Any idea on what causes this issue? Searches reveal that others are having this issue too but I haven't yet found any solutions.
For reference, my URL is http://www.cleverpapers.com
-- you'll see "nav_secondary" at the top of the page and "nav_primary" just under the masthead image.